An altered-temperature inverse suspension polymerization

which was suitable for negatively thermosensitive macromers

was presented to prepare thermosensitive and biodegradable microgels．The thermosensitivity and biodegradability of microgels come from those of rnacromers．The microgels were synthesized in suspension

in which the continuous phase was heptane Ammonium persulphate and N

N

N’

N’-tetramethylethylenediamine were employed as the initiating system．The negatively thermosensitive maeromer aqueous solution was first dispersed well at low temperatures(lower than the sol-gel transition temperature of the macmmer solution) and then crosslinked after raising temperature．The highlight of this approach is the avoidance of dispersion difficulty of the dispersion phase because of its physical gelation at polymerizing temperature．The thermosensitivity and biodegradation of the resulting micmgels were confirmed The volume phase transition temperature of mierogels was around 25℃．and the volume of microgels at 37℃ was less than half of that at 4℃ Mierogels were completely degraded into water-soluble products．It was necessary to add aqueous solutions of initiator and accelerator into the continuous phase after raising temperature．The ratio of oil to water influenced the morphology of miemgels to a certain degree．